Process of coating metals with oxids



Fries.

CRAIG RITCHIE ARNOLD, OF SHARON HILL, PENNSYLVANIA.

PROCESS OF COATING METALS WITH OXIDS.

SPECIFICATION forming part of Letters Patent No. 514,896, dated February20, 1894.

Application filed April 29, 1893- Serlal No. 472,105, (No specimens.)

T on whom it may concern.-

Be it known that I, CRAIG RITCHIE AR- NOLD, a citizen of the UnitedStates, and a resident of Sharon Hill, in the county of DelawareandState of Pennsylvania, have invented a certain new and useful Process ofCoating Metals with Oxids, of which the following is a specification. Y

My invention relates to those processes of coating metals with oxideswhich consists in making the article to be coated the anode of abathcontaining the material for the coating desired in solution, and isdesigned primarily as an improvement upon those processes whichareemployedto give the metal a coating of peroxide of lead.

My invention is designed for use with copper and its alloys, or withiron, steel or'other metals." I

It has heretofore been proposed to coat metals with a bi-oxide of leadby suspending the article in a bath containing nitrate of lead insolution and with or without other materials,and ma I a be coated tpelmdeof the bath, and it has also been proposed; islprocesstosuspendapalhode i nltlqhamber congining a sii'i'fibled'epplarizmg ar enal andchambeijontainingjtlifeibath proper by a? porous m nraw."

My invention consists in immersing the cathode in a solution of causticsoda or its equivalent as hereinafter described, separated from the bathproper by the porous diaphragm.

The oxidizing agents employed previous to my invention foroxidizingthehydrogen set free during the action of blackening or browning themetal with the oxide of lead have some of them been liable to theobjection that if the process be carriedon too rapidly metallic leadwould be deposited on the cathode and its surrounding diaphragm orporous cup. This deposit of metallic lead on the cathode not onlyprevents the oxidation of the hydrogen, but it would so impoverish thesolution by the withdrawal of lead that the bath would become Verysluggish in .its action and it would become necessary to suspendoperations for the time being until a new diaphragm could besubstituted, and the solution be replenished.

It has heretofore been proposed to use dioxide of manganese as theoxidizing substance in connection with the bath containing nitrate oflead in solution for the anode.

My present invention consists in the substitution for the dioxide ofmanganese of a It hasprior to myinvention been proposed to employ a bathfor the anode composed of nitrate of lead and caustic soda or potash.

My present invention consists in the addition to a bath containing thenitrate of lead in solution, of an oxide of lead or its equivalent (ahydrate). The oxide or its equivalent I add in quantities to produce aturbidity in 7 the solution. During plating, the finely powdered oxidemay be added and while the operation is going on thorough motion'shouldbe imparted'to the solution.

To make a bath of the nitrate of lead, I pro ceed as follows:In order toprepare twentytwo gallons of plating bath, dissolve twentytwo .pounds ofnitrate of lead in seven gallons of hot water. This solution is pouredinto eleven gallons of caustic soda of the specific gravity of 1.20,after having warmed it to 70 Centigrade. This solution is kept at thistemperature for say, thirty minutes and mixed well; and after coolingdown, sufficient Water is added to make up the required amount of bath.During plating, finely powdered litharge is added to the bath and duringthe operation thorough agitation should be imparted to the solution. Thearticle to be plated is suspended from the anode pole. The articleto becoated, after being carefully cleansed by any Well known method employedin processes ofelectrical deposition, in order to remove all oxides andfatty material, is immersedin the bath and made the positive pole of acircuit of the dynamo electric malcd chine or other source of energy,and electric current is passed through the bath until the article hasobtained the required deposit. The results produced by this bath aremuch superior to those obtained with baths heretofore proposed.

What I claim as my invention is- 1. The herein described improvement incoating metals by making the article to be coated the anode of a bathcontaining nitrate of lead in solution to which oxide of lead or itsequivalent, as described, is added, as and for the purpose described.

2. The herein described improvement in coating metals by making thearticle to be coated the anode of a bath composed of nitrate of lead andcaustic sodaor potash to CRAIG RITCHIE ARNOLD.

Wit n esses:

J. LENTZ GARRETT, MARY A. MARTIN.

